The present invention relates to a therapeutic medical compression garment. More particularly, the present invention relates to a therapeutic tubular compression hosiery garment having a welt formed at the top with structural features on the inner surface of the welt to contact the skin of the wearer. These structures reduce the tendency of the welt to roll down onto itself, and increase the resistance of the garment from slipping down the limb that is characteristic of prior art hosiery products. For purposes of illustration the invention disclosed in this application refers to garments used on the leg or parts of the length of the leg. The term “garment” is used in this application to mean garments such as body stockings, leg stockings, hose, panty-type hose, socks, arm sleeves and similar tubular structures used on the trunk, arms and legs. A method of constructing compression garments is also disclosed and claimed.
Therapeutic medical compression garments are used to assist in the management of various venous and lymphatic disorders, particularly in the lower extremities of the body. The purpose of the garment is to minimize or eliminate the effects of elevated venous pressures caused by gravity or disease processes by reducing the tendency of blood to pool in the lower extremities. This type of garment may also be applied to inactive or bedridden individuals to reduce the occurrence of clot formation in the lower extremities that can travel to the heart or lungs where a thromboembolism may develop. This type of garment functions by maintaining blood flow and typically has a graduated pressure profile to effect a predetermined compression of the leg sufficient to force blood upwardly out of the extremities and into circulation throughout the body. External circumferential counter pressure maintains the venous and lymphatic pressures at more normal level in the extremity, thus assisting the movement of venous blood and lymph from the extremity. Another important effect of compression is the reduction of venous volume that leads to an increase of venous flow velocity. Edema reduction and prevention is the goal in patients with chronic venous insufficiency, lymphedema, and other edema causing conditions. Subcutaneous pressures increase with elastic compression. This rise in subcutaneous tissue pressure acts to counter transcapillary forces, which favor leakage of fluid out of the capillary.
In order to ensure that the effect of an outside pressure or compression is constantly achieved to the correct extent and at the correct place on the body, it is necessary that the garment be kept in a therapeutically-correct position on the limb. For this purpose, it is known to include so called “anti-slip” structures into the garment. These structures are formed in such a manner that the garment is prevented from sliding along the limb due to the frictional properties of the yarns forming the knit structure and/or due to the elastic properties of the knit structure as a whole.
In addition, because medical efficacy often requires that compression garments be worn for a long period of time, it is desirable to control how much pressure is applied to the limb by the anti-slip structure in order to provide a comfortable fit for the wearer. An uncomfortable or even painful fit may induce the wearer to remove it, reducing or eliminating the desired therapeutic effect.
There are a variety of therapeutic medical compression garments that are known in the art. However, known therapeutic garments have a tendency to slip down the leg of the wearer, thereby detracting from the benefits of the garment. This slippage is often accompanied or caused by the top of the garment rolling down over itself to form a ring of fabric material at the top of the garment.
An example of a therapeutic garment is described in U.S. Pat. No. 3,975,929 to Fregeolle which describes a thigh length anti-embolism garment made with alternating courses of covered spandex yarn knitted on a circular hosiery knitting machine. The garment described in Fregeolle shows a turned welt around a portion of the top of the garment and a narrow elastic band stitched to the upper portion of the garment. The inner face of the elastic band is provided with beads or rows of frictional gripping material that aid in supporting the upper end of the garment on the leg of the wearer by frictionally engaging the leg.
Another example of a therapeutic garment is described in U.S. Pat. No. 3,874,001 to Patience, et al., which discloses a full length garment having a foot and leg portion knitted of elastic. A narrow band of non-slip elastomeric webbing material is sewn onto the upper end of the leg portion by over-stitching. The particular stitching used is said to provide for adequate movement of the knitting loops relative to each other to ensure the deformation of the garment as it is worn.
U.S. Pat. No. 3,983,870 to Herbert, et al. discloses a slip-resistant medical garment that addresses the “slip” problem by coating 20 to 30 percent of the inner surface of the knitted thread with a non-adhesive, non-continuous, relatively soft elastomeric polymeric material with a high coefficient of friction to provide a non-occlusive slip resistant-surface asserted to be capable of maintaining the support in place on the limb of the body.
Yet another type of anti-embolism garment is disclosed in U.S. Pat. No. 3,728,875 to Hartigan, et al. This garment is knitted on a circular hosiery knitting machine and the upper portion is slit downwardly in a walewise direction. A wedge-shaped insert of soft elastic fabric is sewn into the slit to increase the circumference of the upper end of the garment. In garments of this type the sewing of the wedge increases the cost of production. The insert is formed of a different compressive fabric than the remaining portion of the upper end of the garment so that the portion of the leg covered by the insert does not receive the same compressive force as applied to the remaining portion of the leg of the wearer. The garment also has a partial elastic retention band made with a corrugated anti-slip inner surface of urethane elastomer sewn to the upper narrow welt of the garment and projecting above the garment welt so that its top forms a continuous line with the top of the insert.
A more recent compression garment is disclosed in U.S. Pat. No. 6,871,516 to Peeler, et al. The garment disclosed in Peeler is a therapeutic medical compression garment with a knitted anti-slip portion located in the upper area of the garment. The garment functions by placing high friction yarns that comprise part of the welt directly next to the wearer's skin in the area of the welt. The high-friction characteristics result from the inherent qualities of the yarn and the texture formed on the inner side of the welt during the knitting process. However, anti-slip effects achieved solely or principally from the inherent characteristics of the yarns may mimic the effects of other types of high-friction creating materials, such as exposed rubber bands and silicone strips or dots which may pull on body hair as the garment creeps down the leg, causing discomfort.
In addition, as noted above, welts of known compression garments have a tendency to roll downwardly over themselves, which may not only initiate further creeping of the garment down the leg, but can also increase compressive force at the rollover site on the leg, restricting blood flow past the rollover site, and thereby counteracting the otherwise beneficial effects of the progressive compression that is intended to force blood upwardly out of the extremities.
Thus, while improvements have been made to the anti-slip properties of anti-embolism garments there remains a need for an effective, inexpensive therapeutic medical compression garment that will resist slipping down the leg of the wearer and that avoids rollover of the welt and the potentially detrimental effects that can result.